Mill begins his examination of government’s role by identifying a set of “necessary” functions. These are not matters for debate or expediency but are so essential that they are inseparable from the very idea of a civilized society. Crucially, these functions are “necessary” because they create the preconditions of predictability and trust required for a market to function. Without them, long-term investment, capital accumulation, and complex contracts are impossible, and the productive energies of a people are paralyzed.

The most critical of these necessary functions is the provision of security. Mill argues that society’s primary duty, exercised through government, is to provide protection for person and property. When producers cannot be certain that they will be allowed to enjoy the fruits of their labor, they have no incentive to produce more than is necessary for immediate subsistence. This forces the productive classes into dependence on a “predatory class,” making industry and frugality pointless.

When person and property are, to a certain degree, insecure, all the possessions of the weak are at the mercy of the strong. No one can keep what he has produced, unless he is more capable of defending it than others who give no part of their time and exertions to useful industry are of taking it from him. The productive classes, therefore . . . are obliged to place themselves individually in a state of dependence on some member of the predatory class, that it may be his interest to shield them from all depredation except his own. [Book V, Chapter VIII]

This security extends far beyond simple protection from force and fraud. The quality and accessibility of the legal and judicial system are critical, if indirect, components of economic function. Mill notes that where the administration of justice is plagued by delay, vexation, and expense, it imposes a heavy tax on citizens, making it preferable to submit to injustice rather than seek redress. An uncertain or “incognoscible” body of law, as Mill highlights in Book V, Chapter VIII, is as much a threat to security as physical violence, as it paralyzes commercial activity by making contracts and property rights unreliable.

Furthermore, Mill identifies the government’s role in defining and regulating property as another non-optional function essential to social order. This is especially true for land, which he describes as “the inheritance of the human race.” The establishment of rules governing its ownership, use, and transfer is a function “less optional than the regulation of these things, or more completely involved in the idea of civilized society.” Having established this essential foundation, Mill then turns to the vast domain of economic life that lies beyond these necessary duties, articulating his default stance on government action.